1. Field of the Invention
This invention relates to a tilt type steering apparatus for an automobile, and in particular to improvements in a portion for pivotally supporting a steering column constituting the steering apparatus relative to a vehicle body, and achieves the compactness of a tilt adjusting portion.
2. Related Background Art
There is known a steering wheel height adjusting apparatus called a tilt type steering apparatus designed to be capable of changing the height of the steering wheel in conformity with a driver's constitution or driving posture.
As such a tilt type steering apparatus, there is known the apparatus disclosed in U.S. Pat. No. 4,594,909.
The tilt type steering apparatus described in this patent is of the so-called oscillating type in which, as shown in FIG. 1 of the accompanying drawings, a steering column 2 formed into a cylindrical shape to insert a steering shaft 1 thereinto is divided into a lower steering column 3 and upper steering column 4 and the two steering columns are connected together by a support bracket 5 mounted on a vehicle body. The upper steering column 4 is pivotable about cross members 6, 6 provided in the support bracket 5, by a mechanism as shown in FIGS. 2 to 4 of the accompanying drawings.
A restraining mechanism engageable by a tilt lever 7 pivotable about the cross members 6, 6 is provided between the support bracket 5 and the upper steering column 4 so that the upper steering column 4 can be coupled to the support bracket 5 (the pivotal movement of the upper steering column 4 can be made impossible) or the upper steering column 4 can be made displaceable relative to the support bracket 5 (the pivotal movement of the upper steering column 4 can be made possible).
More particularly one end of the upper steering column 4 is pivotally supported on the support bracket 5 by the cross members 6, 6 provided in the support bracket 5 fixed to the vehicle body on the underside or the like of a dashboard 8, and also a first engagement member 9 is fixed to the underside of the upper steering column 4. The underside of the first engagement member 9 forms an arcuate convex surface centering around the cross members 6, 6, and this underside is formed with first engagement teeth 10.
In addition one end (the left end as viewed in FIGS. 2 and 4) of a second engagement member 12 engageable with the first engagement member 7 with the pivotal movement of the tilt lever 7 is pivotally supported on another cross member 11 provided in the support bracket 5. The upper edge of the other end portion (the upper edge of the right end portion as viewed in FIG. 2) of the second engagement member 12 is formed with second engagement teeth 13 engageable with the first engagement teeth 10 formed on the underside of the first engagement member 9.
A roller 15 is supported on a shaft 14 provided in such a manner as to extend between the lower end portions of the tilt lever 7 having its intermediate portion pivotally supported on the cross members 6, 6, and the upper surface of the roller 15 bears against the underside of the second engagement member 12.
Further, an inclined slot 17 formed in a pivotable plate 16 fixed to the tilt lever 7 is engaged by a pin 18 protruding from a side of the second engagement member 12.
With the construction as described above, when the tilt lever 7 is pivotally moved counter-clockwise as viewed in FIG. 2, the roller 15 retracts from below the other end portion (the right end portion as viewed in FIG. 2) of the second engagement member 12 and at the same time, the other end portion of the second engagement member 12 is downwardly displaced on the basis of the engagement between the inclined slot 17 and the pin 18.
As a result, the engagement between the second engagement teeth 13 formed on the upper surface of the other end portion of the second engagement member 12 and the first engagement teeth 10 formed on the underside of the first engagement member 9 fixed to the underside of the upper steering column 4 is released (within a range in which a pin 19 projectedly provided on a side of the upper steering column 4 can be displaced inside an arcuate slot 20 formed in the support bracket 5). The upper steering column 4 thus becomes pivotable about the cross members 6, 6, whereby the height position of a steering wheel fixed to the end portion of the steering shaft 1 inserted in the upper steering column 4 becomes freely adjustable.
If the driver releases the tilt lever 7 after the height position of the steering wheel is adjusted in this manner, the tilt lever 7 will be pivotally moved clockwise as viewed in FIG. 2 by the tensile force of a tension spring 21 and the roller 15 will come into contact with the underside of the other end portion of the second engagement member 12 to push the other end portion of the second engagement member 12 upwardly. This brings the second engagement teeth 13 formed on the upper edge of said other end portion into engagement with the first engagement teeth 10 formed on the underside of the first engagement member 9 fixed to the underside of the upper steering column 4, thus preventing the upper steering column 4 from rotating about the cross members 6, 6.
As a result, the steering wheel is held in its adjusted height position. In this state, a resilient force urging the tilt lever 7 clockwise as viewed in FIG. 2 is imparted to the tilt lever 7 by the tension spring 21 and therefore, the roller 15 does not inadvertently retract from below the second engagement member 12.
In the case of the prior-art tilt type steering apparatus constructed and used as described above, in order to secure the rigidity of the shaft 14 to secure the strength of the meshing engagement between the first engagement teeth 10 and the second engagement teeth 13, the opposite end portions of this shaft 14 are suspended by a pair of suspension arms 22 and 22 having their upper end portions pivotally supported on the cross members 6, 6. Consequently, the structure for supporting the shaft 14 becomes complex and bulky and costs are increased.
The heretofore known oscillating tilt type steering apparatuses also include the apparatus disclosed in Japanese Laid-Open Utility Model Application No. 62-4470, but this apparatus has also suffered from a similar problem.